I built mine tonight and it works great. I had some of the same problems with parts and thought I might offer my solutions. I apologize if this is mentioned before.
I bought the Crown Bolt Create a Bolt kit in 5/8". There are two boxes of these at my HD. One is SS and the other is Zinc. I had to poke around but I found the SS ones. Keep looking through the packages, because they look identical minus a small note on the front that designates SS or Zinc. This came with 4 5/8" SS washers and I used all of them. I used 2 5/8" zinc flat washers for the outside spacers. I also added 2 neoprene 5/8" washers. These were in the specialty washers drawer at the HD.
For the spacers, I used the 2 zinc flat washers and 3 SS washers from the kit (since I wasn't going to use them for anything else) and I added a neoprene against the cooler. On the inside, I used the second neoprene, the original rubber seal, and a SS washer.
My HD also said they didn't carry a 3/8" ball valve. So, I bought the 1/2" ball valve and also bought 2 1/2" MIP x 3/8" FIP Pipe Hex Bushing (Watts A-828). I put these on both ends of the 1/2" valved effectivly necking it down to 3/8", which allowed me to use all the other parts without modification.
Also, the local HD did not have much in the way of SS supply hose. It was all polymer except one labeled universal dishwasher hose. The only downside is that it was $15 and came in one length, 60"! Guess I'll have plenty for replacement!